Keyboard data entry devices for electronic data processing systems and word processing systems, and the like, are designed such that key closures are detected for a specific key actuator displacement. It often occurs that the keyboard operator depresses a key with a force that moves the key very close to the specified distance needed for closer detection. Due to fluctuations in the force applied by the key operator, the specified distance may be provided during the first scan cycle, may not be provided during a second scan cycle, and may once again be provided during a third scan cycle. In this case, a key closure is encoded during the first and third scan cycles when it is desired that only one key closure be encoded. The use of mechanical hysteresis to prevent the undesirable multiple encoding problem has not been totally successful.
There are instances where it is desirable to provide multiple encoding for one key closure such as a repeat key function, for example, an underlining function. To ensure that the repeat function is actually intended, it is desirable to have a delay built into the encoding system such that the repeat key must be depressed a minimum time before multiple encoding is initiated. The prior art has not produced a satisfactory repeat key encoding system.